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I first filled it up with RO/DI water, TDS zero, PO4 zero (Hanna checker)

let it sit with a power head for 3 hours, measured the po4 again, and it was up to 0.1 PPM !!! po4 leaching out of food grade container?

I then added salt and mixed it to SG of 35 PPT. measured the PO4 3 hours later, and it is still at 0.1 PPM !!!!!

puzzled by this, I did more research to find out that RO/DI water, and Ultrapure water are very aggressive due to lack of elements and traces, so they attack the plastic, and WILL make it leach ... (only lab grade plastic is safe ? ) [does this make sense to the chemists here ? ]

I was also told that, if I placed some clean aragonite at the bottom of the brute container , the RO/DI water will attack that instead, pulling out CA++, MG++, and carbonates, and would not make the plastic leach out po4 [does this make sense to the chemists here ? worth a try ? ]

I then made a salt water mix in a glass tank, po4 was zero. transfered that to the Brute can ... tested 3 hours later and I got reading of 0.01 PPM ! for po4. so I guess it is the RO/DI water attacking the plastic ?

so putting all these together, I started thinking I should add like quarter of a cup of salt into the empty and clean container, and then make RO/DI water in the container, this way, it will dissolve the salt instead of the plastic ? and I can add more salt once the bucket is full to bring up to the needed SG. ? would this make sense ? would it cause precipitation ?

I know a bit of po4 is nothing ... but I am running a low nutrition system and want to eliminate all extras from the source water at least. would what I said above help ? or am I better of making a tall Acrylic tank for mixing Salt water and Top off ?

Well, keep in mind that the requirements for "food grade" are different than what a reefer may require. In the food world, there is a term "acceptable level of filth."

Plastics have quite the potential to leach some materials into water so I'm not surprised by your findings.

What I can offer you is that there is a finite amount of phosphates/by products in the tub. So in theory, over time, you should read less and less phosphate contamination. You can also rinse the walls with a vinegar solution to help remove any residue that remains.

Also, water doesn't attack or degrade plastic. It's just that when forming the plastic, there are byproducts that are not fully removed. It is those byproducts that are leaching into water.

well RO/DI water does, that is why you are advised not to drink it !! it will harm you liver and stomach and can burn ... (by pulling element and ... from your body)

but good point on food grade ... (what is gov. feeding us :P jks) I was under the impression it wont leach nothing due to seeing so many reefers say they uised it with no ill effects (the good old 'no ill effects' haha)

thanks, seems like glass is the best way, I already made my ATO glass, now need to make one for the salt mixing

well RO/DI water does, that is why you are advised not to drink it !! it will harm you liver and stomach and can burn ...

No, you misunderstood his distinction. Water at room temperature does not degrade polyethylene plastic (as in a Rubbermaid Brute can). Zero. Nada. Absolutely positively zero degradation.

But impurities on or in the plastic, added intentionally or from a bird in the store crapping on it, those are what can come off.

Most of those will be readily removed by a single cleaning, if you are concerned, and that is a fine plan. Such impurities cannot and will not provide a substantial ongoing source of problematic phosphate.

Also, please do not scare monger. Drinking pure DI water does not hurt your liver. Please read any of the hundreds of threads on this topic in this forum and others at Reef Central.

DI/RO water is devoid of healthy minerals (and relatively acidic), but I don't think it is harmful to drink. Distilled water is essentially the same thing, but we don't want to have a distillery going in the back yard!!

FWIW, I always dump the first tubs of water from a new bucket or whatever. I think the brute will be fine if you just soak it and dump the water.

well RO/DI water does, that is why you are advised not to drink it !! it will harm you liver and stomach and can burn ...

No, you misunderstood his distinction. Water at room temperature does not degrade polyethylene plastic (as in a Rubbermaid Brute can). Zero. Nada. Absolutely positively zero degradation.

But impurities on or in the plastic, added intentionally or from a bird in the store crapping on it, those are what can come off.

Most of those will be readily removed by a single cleaning, if you are concerned, and that is a fine plan. Such impurities cannot and will not provide a substantial ongoing source of problematic phosphate.

Also, please do not scare monger. Drinking pure DI water does not hurt your liver. Please read any of the hundreds of threads on this topic in this forum and others at Reef Central.

I didnt mean it will degrade the pastic and break it in half, I meant it will pull out the PO4 within the plastic, as you said, impurities added to the plastic in manufacturing and ....
(sorry, my English is not that good, so maybe I use the wrong words once in a while, please try to see the bigger pic Im asking about)

about problematic po4 ... well Id like to get as clean as I can I know this po4 wont crash my SPS tank, but life would be better without it, no ? or do we want some impurities ? my tap water has po4 of 0.07 PPM ! I use a RO/DI unit to lower that

also about drinking DI water ... DI water is aggressive, I hope we can agree on this ? it will even pull out impurities from AIR, right ? if so, then what makes you think it will not do the same once you drink it ? it is going to pull stuff out of our body ...

DI/RO water is devoid of healthy minerals (and relatively acidic), but I don't think it is harmful to drink. Distilled water is essentially the same thing, but we don't want to have a distillery going in the back yard!!

FWIW, I always dump the first tubs of water from a new bucket or whatever. I think the brute will be fine if you just soak it and dump the water.

from what I understand, RO/DI Water is more pure than distilled water, it has PH of 7.0 and is neutral ...

From our perspective, there is no practical difference between RO/DI and distilled, but exactly what impurities may remain vary a bit. For example, atmospheric gases like O2, CO2, N2, etc, may be different. Certain impurities in the starting water can also get through distillation and RO/DI, but how much depends on what might have been there.

RODI will not kill you or harm you. you are thinking of lab grade ion free water.. that stuff will pull the ions and elements from your body. i work in biotech and our lab uses this stuff all the time in testing. it will make you sick. and tastes bad. hehe
you could always add some salt to the water to brine it up. i use 55g and 20g drums from my pharma that stored 6mm guanidine and high purity sucrose that would make you sick to eat it its so purified. hehe you could always try to find a drum liner to cover the drum.

High purity water is simply water. It is not magical or dangerous. It has no magical ability to pull anything from your body if consumed (where are these ions going to go anyway?). You would have to be on a very odd low ionic diet, and then drink large amounts of high purity water to have a negative effect on the human body.

I had several catridges I needed to use up on an old millipore water machine that one of my old institutions planned to get rid of. I consumed around 8-10 liters of 18.2Mohm water per day for about a month. This was in a very arid environment where my daily liquid consumption was around 12-14 liters per day. I survived, and had a normal blood and urine electrolyte balances per my monthly physical (little low on urine specific gravity, but that was preferred medically for that environment). My diet provided all the nutrients and ion loading I needed. Honestly, your average 1st world human consumes more ions than needed.

High purity water is not particularly acidic, or basic. It is also virtually impossible to get a meaningful pH measurement on very pure water sources as these is such a low ionic balance, that the results are meaningless. Default value of OH and H ions is equal, hence the pH is 7. Atmospheric gasses will drive measure pH down quickly, especially with a 380-390ppm balance of CO2 based on global averages. This does not mean acidic, as much as non-buffered.

As far as leeching goes, pure water has such a low concentration gradient in it, that it is easier to dissolve ionic substances in over less pure waters. This is more a factor of the contribution of other ions than the 'aggresive nature' of water. It is simply easier for the majority of people to understand if you call it aggresive versus saying that it is readily accepting of any ion dissolution from the water's containment.

So back to the original topic. That PO4 coming off the can isn't doing so as strictly a result of the high purity water. As your salt water test proved, it is there in the plastic as a contaminate, even the salt water had some orthophosphate dissolve into it.

HDPE sample bottles need to be well cleaned prior to use for lab grade studies.

And to add some randomness, things like hexavalent chromium, arsenate, and nitrites will give positives on ascorbic acid reduced phosphate methods.